6.3

CVE-2026-59980: python-hyper hpack Uncontrolled Resource Consumption

CVSS: 6.3v4.0MediumDeferred
AliasesMGASA-2026-0349SUSE-SU-2026:4593-1GHSA-8v8h-hg4w-mvq2
Published 23-09-2026Last modified 24-09-2026
Open JSON

Vulnerability summary

CVE-2026-59980 is a medium (CVSS 6.3) Uncontrolled Resource Consumption vulnerability in python-hyper hpack. EPSS estimates a 0.30% chance of exploitation in the next 30 days, higher than 21.4% of scored vulnerabilities.

Overall risk
25/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.3/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.30%
0%100%
Low · Change unavailable
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
OPENSUSE-SU-2026:11556-1

Timeline

  1. 23-09-2026
    PublishedVulnerability first disclosed.
  2. 24-09-2026
    Last modifiedVulnerability information updated.

Description

hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use.

CVSS metrics

6 scores · 6 sources · 1 version

EPSS trend

Probability

0.30%

Chance of exploitation in the next 30 days

Percentile

21%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

24-09-202619-10-2026
EPSS score
0.30%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard3 products
  • airflow-2< 2.11.2-r24
  • authentik-2025.12< 2025.12.6-r14
  • authentik-fips-2025.12All versions (No fix recorded)
Debian1 product
  • python-hpackAll versions (No fix recorded)
Mageia1 product
  • python-hpack< 4.2.0-1.mga10
PyPI1 product
  • hpack< 4.2.0
Python-hyper1 product
Suse1 product
  • python-hpack&distro=SUSE Linux Enterprise Module for Server Applications 15 SP7< 3.0.0-150200.3.5.1
Ubuntu1 product
  • python-hpackAll versions (No fix recorded)

7 vendors · 9 products

References

18 links
Show all 18 references